1. Field
The present invention relates to a heat exchanger for a condensing type clothes or laundry dryer.
2. Background
In general, a drying apparatus such as a clothes dryer or a washing machine having a drying function, dries clothes by blowing hot air generated by a heater into a drum. Such dryers can be divided into exhausting (or vented) type dryers and condensing type dryers, depending on the method used for processing the humid air generated when drying clothes. In the exhausting or vented type dryer, humid air exhausted from a drum is discharged to the outside of the dryer. In the condensing type dryer, humid air discharged from the drum is condensed to remove the moisture therefrom, and the dried air is conducted back into the drum again so as to be re-circulated.
A condensing type dryer typically includes a drum for containing laundry, a filter for filtering out lint and foreign materials, and a heat exchange unit (or condenser) for removing moisture from hot drying air which has flowed through the drum and absorbed moisture from the laundry therein. The dryer also includes a fan for facilitating the drying operation by generating air flow, a heater for heating the air flow to shorten the drying time, and pipes or vents for connecting the components.
FIG. 1 is a side view schematically showing the internal components of an example of a condensing type dryer. FIG. 2 is an interior plan view of the condensing type dryer of FIG. 1. FIG. 3 is a perspective view of a heat exchanger in the dryer of FIG. 1, and FIG. 4 is a lateral side view of the heat exchanger of FIG. 3. The arrows I indicate a flow of external cold air, and the arrows II indicate a flow of circulating hot air.
Referring to FIGS. 1 and 2, a drum 11 in which laundry is to be accommodated is rotatably installed inside a main body 10 which is provided with a door 12 installed at a front surface thereof. The drum 11 is rotated by a belt 19 connected to a motor 17 installed at a lower portion of the main body 10. A heat exchanger (or condenser) 13 is installed at a lower portion of the main body 10 and condenses moisture from hot and humid air that has been circulated through the drum 11 to remove the moisture from the air. Circulation ducts 14a and 14b which are respectively connected with the front and rear end of the drum 11 are connected with the front and the rear portions of the heat exchanger 13, respectively. When air is discharged from the drum 11, it can be introduced again into the drum 11 after passing through the heat exchanger 13.
A heater 15 for heating air which has passed through the heat exchanger 13 and a circulation fan 16 for forcibly circulating the air through the circulation ducts 14a and 14b are installed at the circulation duct 14a. The circulation fan 16 is connected with a different shaft of the motor 17 that also drives the drum 11.
In order to condense moisture from air circulated through the circulation duct 14a, a heat exchanging operation is conducted using external cold air supplied to the heat exchanger 13. For this purpose, an external air supply duct 18 which communicated with the exterior of the main body 10 is connected with one side of the heat exchanger 13. A cooling fan 20 forcibly sucks in external air through the external air supply duct 18 and discharges it into the main body 10. A cooling fan driving motor 21 drives the cooling fan 20. A filter 22 is used to filter out foreign materials such as lint and waste thread or the like from the air exhausted to the circulation duct 14a through the front end side of the drum 11.
A water receiver (not shown) for collecting the water condensed during the condensation process is installed below the heat exchanger 13. A pump 23 is used to pump the condensed water collected in the water receiver to a condensed water storage tank 2.
Referring to FIG. 3, the external air passes through the lateral side surfaces of the heat exchanger 13 in the direction of the arrows I, and the circulating air passes through the front and rear ends of the heat exchanger 13 in the direction of the arrows II. Through this process, heat exchange occurs in the heat exchanger 13 between the external air and the circulating air. The circulating air is cooled, which causes moisture in the circulating air to condense and thereby be removed from the drum 11. The cooled and dried circulating air is then heated and blown into the drum 11 again so as to be re-circulated.
When moisture is condensed in the heat exchanger, it flows to the exposed lower end portion of the heat exchanger 13. The condensed water collects at the lower end portion of the heat exchanger 13 (the part shown encircled by the dashed line in FIG. 3), which causes an airflow resistance, and the performance of the heat exchanger 13 is deteriorated. Also, due to the obstruction caused by the pooled condensed water, the flow of the external cold air is forced towards the lateral edge regions of the heat exchanger 13, as shown within the dashed lines in FIG. 4. As a result, it is difficult to ensure a uniform distribution of the external air flow. As a result, a drying performance of the dryer may become deteriorated.